The present invention relates to a rotor structure, especially for hingeless rotary wing aircrafts.
German Pat. No. 1,531,359 discloses a rotor of the type to which the invention relates. In such a rotor, the torsionally yielding connection of the respective pair of rotor blades passes freely through the rotor head center so that the cyclical blade angle adjustment of the two diametrically opposite each other located rotor blades does not result in any twisting of the torsionally yielding connection. In the cyclical blade angle adjustment the two rotor blades of a pair are tilted in the same direction and to the same extent. Thus, the torsion loading of the torsionally yielding connection of the blades of a pair is determined solely by the collective blade angle adjustment. However, practical experience has shown that it is not possible to do without a centering holding structure for securing a rotor blade pair to the rotor head. Such centering holding structure is necessary due to unbalances and vibrations in the longitudinal rotor blade axis. Hence, the just described rotor has not achieved any practical significance.
German Pat. No. 2,150,741 discloses the connection of the rotor blades to the rotor head. It has been customary heretofore to construct the torsionally yielding connections in the form of tension members which connect but one rotor blade root to a central rotor head body which extends coaxially to the rotational axis of the rotor head. This type of structure makes it impossible to avoid that the respective torsional connecting member is twisted in response to each angular movement of the individual rotor blade, said twisting extending all the way to the central rotor head body.